Method and apparatus for aligning probe pins with respect to positions of electronic devices

ABSTRACT

A method for aligning probe pins with respect to positions of electronic devices comprises conducting contact stamping on a first electronic device with the probe pins to form first probe marks on lead pads of the first electronic device, capturing an image of the first electronic device, determining positions of the first probe marks on the first electronic device using the captured image, calculating an offset using the positions of the first probe marks, adjusting relative positions between a subsequent plurality of electronic devices and the probe pins using the offset, and contacting lead pads of the subsequent plurality of electronic devices with the probe pins for testing said electronic devices. The first probe marks are configured to have greater visibility as compared with second probe marks formed when contacting the lead pads of the subsequent plurality of electronic devices with the probe pins, so as to improve the accuracy of the offset calculated.

FIELD OF THE INVENTION

The present invention relates to a method and apparatus for aligningprobe pins with respect to positions of electronic devices for testingthe electronic devices more effectively.

BACKGROUND OF THE INVENTION

FIGS. 1A and 1B respectively show a plan view and a perspective view ofan exemplary electronic device 100. As shown in FIGS. 1A and 1B, theelectronic device 100 comprises a plurality of electrical lead pads 102.These lead pads 102 are used for the connection of the electronic device100 to other electronic components.

To check if an electronic device operates as desired, the electronicdevice is usually subjected to various tests after its fabrication. Thisis typically performed by probing lead pads of the electronic device. Toelaborate, probe pins (or in other words, contact pins) are brought intocontact with the lead pads of the electronic device to connect thedevice to a tester. The tester sends signals to the electronic deviceand analyzes the electronic device's responses to determine if thedevice is working properly. As the signals to the device and theresponses from the device are relayed via the connections between thelead pads and the probe pins, it is important to ensure properelectrical contact between the lead pads and the probe pins.

Ideally, the probe pins should contact the centres of the respectivelead pads. FIG. 2 shows such an ideal situation. In particular, FIG. 2shows a plan view of an electronic device 200 having a plurality ofprobe marks 204 at the centres of respective lead pads 202. The probemarks 204 indicate positions of the probe pins when the probe pins arebrought into contact with the lead pads 202. Indentations with aparticular depth are formed by the probe pins, depending on the force atwhich the device 200 is urged against the probe pins, the materialcomposition of the lead pads and/or the number of times such urgingoccurs.

In order to get as close to the ideal situation as possible, thepositions of the probe pins may be adjusted during the testing process.Conventionally, this is done by determining the positions of the probemarks on the lead pads after testing each electronic device and based onthis determination, adjusting the positions of the probe pins for thenext electronic device. To elaborate, after testing an electronic devicethat is held on a turret of a test handler, a camera captures an imageof the electronic device to try to detect the positions of the probemarks on the lead pads of the device. The difference between thepositions of the probe marks and the centres of respective lead pads isthen calculated and used to adjust the positions of the probe pins. Theturret of the test handler then retrieves a next electronic device fortesting using the adjusted positions of the probe pins. Theafore-mentioned steps are repeated for each electronic device.

A problem with the above approach is that it is often difficult todetect accurately the positions of the probe marks from the imagecaptured after testing the electronic device. This is due to “noise” inthe captured image which may be caused by unrelated features and/ordefects in the electronic device. In turn, a number of tests with theprobe pins in less than ideal positions may have to be performed beforethe difference in the positions of the probe marks and the centres ofrespective lead pads can be accurately calculated. This thereforeresults in low yield as many electronic devices tested at the beginningof the testing process may be wrongly classified as defective.

To overcome the above problem, methods to reduce the noise in thecaptured images have been developed. One such method involves performingvarious operations on the captured image to obtain one or moreinspection result images, each based on a unique image characteristic ora unique combination of image characteristics. Each inspection resultimage is then correlated with a reference image to determine which imagecharacteristic or combination of image characteristics is likely toprovide the necessary contrast. The image characteristic or combinationof image characteristics most likely to provide the necessary contrastis then used for the processing and inspection of subsequent capturedimages. Although such a method may help increase the accuracy indetermining the probe marks' positions, it is unlikely that it cansufficiently improve the production yield. This is because there aremany potential sources of noise in each captured image and the capturedimages of a plurality of electronic devices can differ from one anotherby a non-negligible amount. Therefore, it is unlikely that the methoddescribed above can sufficiently compensate for the noise in all thecaptured images to the extent that the probe marks positions can bedetected at a high enough accuracy for every image.

SUMMARY OF THE INVENTION

The present invention aims to provide a new and useful method andapparatus for aligning probe pins with respect to positions ofelectronic devices.

In general terms, the present invention proposes calculating an offsetusing a first electronic device and using the offset for a subsequentplurality of electronic devices. Both the first electronic device andthe subsequent plurality of electronic devices are contacted with theprobe pins, with the probe marks formed on the first electronic devicebeing formed more visibly than the probe marks formed on the subsequentplurality of electronic devices.

Specifically, a first aspect of the present invention is a method foraligning probe pins with respect to positions of electronic devices, themethod comprising: conducting contact stamping on a first electronicdevice with the probe pins to form first probe marks on lead pads of thefirst electronic device; capturing an image of the first electronicdevice; determining positions of the first probe marks on the firstelectronic device using the captured image; calculating an offset usingthe positions of the first probe marks; adjusting relative positionsbetween a subsequent plurality of electronic devices and the probe pinsusing the offset; and contacting lead pads of the subsequent pluralityof electronic devices with the probe pins for testing said electronicdevices, the contacting of the lead pads of the subsequent plurality ofelectronic devices with the probe pins forming second probe marks,wherein the first probe marks formed during the contact stamping areconfigured to have greater visibility as compared with the second probemarks.

By forming probe marks having greater visibility on the first electronicdevice, the positions of the probe marks can be more accuratelydetermined. In turn, the offset can be more accurately calculated, andthe adjustment of the relative positions between the subsequentelectronic devices and the probe pins can be more accurate. Hence, lessof the subsequent electronic devices will be wrongly classified asdefective and overall, a higher yield can be achieved. The setup time ofthe apparatus (corresponding to the time taken to obtain an accurateoffset) can also be reduced. Further, unlike prior art methods, themethod of the above-mentioned first aspect uses a constant offset foreach subsequent electronic device instead of calculating an offset aftercontacting each device with the probe pins. This thus helps to improvethe efficiency, thereby increasing the yield.

Preferably, the method further comprises the following steps prior tothe step of conducting contact stamping on the first electronic devicewith the probe pins: retrieving the first electronic device with ahandling member; and determining a position of the first electronicdevice relative to the handling member.

Also preferably, the step of adjusting the relative positions betweenthe subsequent plurality of electronic devices and the probe pins usingthe offset comprises: retrieving a subsequent electronic device with thehandling member; determining a position of the subsequent electronicdevice relative to the handling member; calculating a difference betweenthe position of the subsequent electronic device relative to thehandling member and the position of the first electronic device relativeto the handling member; and adjusting the relative position between thesubsequent electronic device and the probe pins using the offset and thecalculated difference.

By taking into account the difference in positions of the first andsubsequent electronic devices relative to the handling member, theadjustment of the relative positions between the subsequent electronicdevice and the probe pins can be more accurate. This is because theoffset is calculated using the first electronic device but the handlingmember may retrieve the subsequent electronic device at a positiondifferent from the position of the first electronic device.

The step of adjusting the relative position between the subsequentelectronic device and the probe pins may be conducted by an adjustingstation that is integrated with a contactor station for testing theelectronic device such that the adjusting station and the contactorstation form a single station. This reduces the number of stations ofthe apparatus. In turn, the size of the apparatus is reduced, and themanufacturing and maintenance costs of the apparatus are lowered.

The step of adjusting the relative positions between the subsequentplurality of electronic devices and the probe pins using the offset mayfurther comprise the step of adjusting positions of the probe pins usingthe single station. By adjusting the positions of the probe pins insteadof the position of the electronic device, the handling member need notrelease the electronic device prior to the contact stamping process.This helps to increase the efficiency of the process.

Alternatively, the step of adjusting the relative position between thesubsequent electronic device and the probe pins may be conducted by anadjusting station that is separate from a contactor station for testingthe electronic device. The step of adjusting the relative positionsbetween the subsequent plurality of electronic devices and the probepins using the offset may be performed by the adjusting station withrespect to the handling member prior to the contacting of the lead padsof the subsequent plurality of electronic devices with the probe pins.

The step of determining the position of the first electronic devicerelative to the handling member may comprise capturing an image of thefirst electronic device and determining the position using the capturedimage. This allows the position to be determined quickly using imageprocessing techniques well known in the art.

The step of capturing the image of the first electronic device prior tothe step of conducting contact stamping on the first electronic devicewith the probe pins and the step of capturing the image of the firstelectronic device after the step of conducting contact stamping on thefirst electronic device with the probe pins may be conducted using asingle imaging station. This reduces the size of the apparatus and sincesuch an apparatus comprises fewer stations, the manufacturing andmaintenance costs of the apparatus can be reduced.

Alternatively, the step of capturing the image of the first electronicdevice prior to the step of conducting contact stamping on the firstelectronic device with the probe pins may be conducted using one imagingstation and the step of capturing the image of the first electronicdevice after the step of conducting contact stamping on the firstelectronic device with the probe pins may be conducted using anotherimaging station. Having two separate imaging stations for the imagecapturing before and after the contact stamping can smoothen the processflow.

The method may further comprise adjusting a relative position betweenthe first electronic device and the probe pins prior to the step ofconducting contact stamping on the first electronic device with theprobe pins. This can help reduce the distance between the probe pins andthe centres of the respective lead pads during the contact stampingprocess, so that the probe marks formed are not too far from the centresof the lead pads. This in turn facilitates the detection of the probemarks from the captured image.

Calculating the offset may comprise determining differences in thepositions of the first probe marks and centres of respective lead padsof the first electronic device the first probe marks are formed on. Thishelps to achieve as close to the ideal situation as possible later onwhen adjusting the relative positions between the subsequent electronicdevices and the probe pins using the offset.

The first probe marks may be formed to have a first level of depth andthe second probe marks may have a second level of depth, the secondlevel of depth being less than the first level of depth. Forming deeperprobe marks provides a straightforward way of increasing the visibilityof the first probe marks.

Conducting contact stamping on the first electronic device with theprobe pins to form the first probe marks having the first level of depthmay comprise stamping the first electronic device with the probe pinsmultiple times. This provides a straightforward way of forming deeperprobe marks which are more visible in the subsequently captured image ofthe device.

The step of adjusting the relative positions between the subsequentplurality of electronic devices and the probe pins using the offset maybe conducted manually using an adjusting station including a gaugeconfigured to facilitate manual adjustment of positions of theelectronic devices or the probe pins. This allows the user to performmanual adjustment of the positions of the devices or the probe pins moreaccurately.

A second aspect of the present invention is an apparatus for aligningprobe pins with respect to positions of electronic devices, theapparatus comprising: a contactor station configured to conduct contactstamping on a first electronic device with the probe pins to form firstprobe marks on lead pads of the first electronic device and to contactlead pads of a subsequent plurality of electronic devices with the probepins to conduct testing of the subsequent plurality of electronicdevices with the probe pins, which testing forms second probe marks, thefirst probe marks formed during the contact stamping being configured tohave greater visibility as compared with the second probe marks; animaging station configured to capture an image of the first electronicdevice after the contact stamping of the first electronic device withthe probe pins; a processing module configured to determine positions ofthe first probe marks on the first electronic device using the capturedimage and to calculate an offset using the positions of the first probemarks; and an adjusting station configured for adjusting relativepositions between the subsequent plurality of electronic devices and theprobe pins using the offset prior to the testing of the subsequentplurality of electronic devices with the probe pins.

BRIEF DESCRIPTION OF THE FIGURES

Embodiments of the invention will now be illustrated for the sake ofexample only with reference to the following drawings, in which:

FIGS. 1A and 1B respectively show a plan view and a perspective view ofan exemplary electronic device;

FIG. 2 shows an ideal situation in which probe marks coincide withcentres of respective lead pads of an electronic device;

FIG. 3 shows an apparatus for aligning probe pins with respect topositions of electronic devices according to a first embodiment of thepresent invention;

FIGS. 4A and 4B show perspective views of uplook cameras of theapparatus of FIG. 3;

FIG. 5 shows a perspective view of an XYT table of the apparatus of FIG.3;

FIG. 6A shows a perspective view of a contactor station of the apparatusof FIG. 3 and FIG. 6B shows a contact stamping process at the contactorstation of FIG. 6A;

FIG. 7 shows a flow chart of a part of a method performed by theapparatus of FIG. 3;

FIG. 8 shows a flow chart of another part of the method performed by theapparatus of FIG. 3;

FIGS. 9A and 9B respectively show plan views of an electronic devicewith probe marks offset from and coinciding with centres of respectivelead pads;

FIG. 10 shows an apparatus for aligning probe pins with respect topositions of electronic devices according to a second embodiment of thepresent invention;

FIG. 11A shows a perspective view of an XYT table of the apparatus ofFIG. 10 and FIG. 11B shows an enlarged view of a part of the XYT tableof FIG. 11A,

FIG. 12 shows a flow chart of a part of a method performed by theapparatus of FIG. 10;

FIG. 13 shows a flow chart of another part of the method performed bythe apparatus of FIG. 10;

FIG. 14 shows an apparatus for aligning probe pins with respect topositions of electronic devices according to a third embodiment of thepresent invention; and

FIG. 15 shows an apparatus for aligning probe pins with respect topositions of electronic devices according to a fourth embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 3 shows a plan view of an apparatus 300 for aligning probe pinswith respect to positions of electronic devices according to a firstembodiment of the present invention.

The apparatus 300 comprises a loading station 302 configured to receiveelectronic devices, first and second imaging stations 304, 310configured to capture images of the electronic devices, an adjustingstation 306 configured to adjust positions of the electronic devicesrelative to the probe pins, a contactor station 308 comprising the probepins, an offloading station 312 configured to allow electronic devicesto be offloaded from the apparatus 300 and a transfer member 314configured to transfer the electronic devices between the stations302-312. Although not shown in FIG. 3, the apparatus 300 furthercomprises a processing module in the form of a computer configured toprocess the captured images.

The transfer member 314 comprises a turret having a main circular bodyand multiple handling members in the form of electronic device holdersarranged equidistantly along the circumference of the main circularbody. Each electronic device holder is configured to carry an electronicdevice. The stations 302-312 are arranged around the main circular bodyand the main circular body is configured to rotate so as to transfer theelectronic devices between the stations 302-312.

The first and second imaging stations 304, 310 each comprises an imagecapturing device in the form of an uplook camera. FIGS. 4A and 4B showperspective views of the uplook cameras 402, 404 of the first and secondimaging stations 304, 310 respectively. As shown in FIGS. 4A and 4B, theuplook camera 402 of the first imaging station 304 serves to capture animage of the electronic device 406 before it is brought into contactwith the probe pins, whereas the uplook camera 404 of the second imagingstation 310 serves to capture an image of the electronic device 406after it is brought into contact with the probe pins.

The adjusting station 306 comprises an adjusting member in the form ofan XYT table having movable elements and motors configured to drive themovable elements. FIG. 5 shows a perspective view of the XYT table 502of the adjusting station 306. As shown in FIG. 5, the XYT table 502comprises a first movable element 506 configured to move along two axes(X and Y axes) of a plane and a second movable element 508 configured torotate in a θ direction parallel to the plane. Therefore, by placing theelectronic device 504 on the second movable element 508, and driving themovable elements 506, 508 with the motors, the position of theelectronic device 504 can be adjusted.

FIG. 6A shows a perspective view of the contactor station 308. Thecontactor station 308 comprises a socket 604 and probe pins 606 at thebase of the socket 604. FIG. 6B shows a contact stamping process whereinthe probe pins 606 are brought into contact with an electronic device602. As shown in FIGS. 6A and 6B, the socket 604 is shaped to receivethe electronic device 602 and the probe pins 606 are arranged so as tocontact respective lead pads 608 of the electronic device 602 when theelectronic device 602 is placed in the socket 604 and urged against theprobe pins 606.

In use, the apparatus 300 performs a method for aligning probe pins withrespect to positions of electronic devices as shown in FIGS. 7-8.

In particular, the method comprises steps 702-718 (as shown in FIG. 7)to calculate an offset using a first electronic device, and steps802-812 (as shown in FIG. 8) which uses the offset for testing asubsequent plurality of electronic devices. Steps 702-718 and 802-812are described in detail below.

In step 702, a first electronic device is loaded onto the loadingstation 302.

In step 704, the first electronic device is transported by the transfermember 314 to the first imaging station 304 and an initial image of thefirst electronic device is captured by the uplook camera 402 at thefirst imaging station 304. In particular, an electronic device holder ofthe turret retrieves the first electronic device from the loadingstation 302 and as the main circular body of the turret rotates, theelectronic device holder transports the first electronic device to thefirst imaging station 304. The electronic device holder then holds thefirst electronic device a distance above the camera 402 to capture theinitial image.

In step 706, the position of the first electronic device relative to theelectronic device holder is determined by the processing module usingthe initial captured image. This may be done by image processingtechniques well known in the art.

In step 708, the first electronic device is transported to the adjustingstation 306 and a rough adjustment of the device's position isperformed. In particular, the main circular body of the turret rotatesto move the electronic device holder carrying the first electronicdevice to the adjusting station 306. The first electronic device isplaced onto the second movable element 508 of the XYT table 502 and itsposition relative to the electronic device holder is adjusted by drivingthe motors of the XYT table 502 to move the first and/or second movableelements 506, 508. This rough adjustment is based on the position of thefirst electronic device as determined in step 706.

In step 710, the first electronic device is transported to the contactorstation 308 to perform a contact stamping process on the firstelectronic device (in other words, to contact the first electronicdevice with the probe pins 606). This is done by having the electronicdevice holder pick up the first electronic device from the XYT table 502in its adjusted position and rotating the main circular body of theturret so as to move the electronic device holder to the contactorstation 308. At the contactor station 308, while holding the firstelectronic device in its adjusted position, the electronic device holderurges the device against the probe pins 606 multiple times to form probemarks having a first level of depth on the lead pads of the firstelectronic device to increase the visibility of the probe marks.

In step 712, the first electronic device is transported to the secondimaging station 310 and a further image of the electronic device iscaptured using the uplook camera 404 of the second imaging station 310.The electronic device holder moves the first electronic device away fromthe socket 604 and with the rotation of the main circular body of theturret, the electronic device holder moves from the contactor station308 to the second imaging station 310. An image is captured by theuplook camera 404 while the first electronic device is held above and adistance away from the camera 404 by the electronic device holder.

In step 714, the positions of the probe marks on the lead pads of thefirst electronic device are determined by the processing module usingthe further captured image. Again, this may be performed by imageprocessing techniques well known in the art.

In step 716, an offset (comprising X, Y and θ components correspondingto the X, Y and θ directions as shown in FIG. 5) is calculated using thepositions of the probe marks as determined in step 714. FIG. 9A shows anexemplary first electronic device 900 with probe marks 902 offset fromthe centres 904 of respective lead pads 906. Such probe marks 902 areformed on the first electronic device 900 in step 710. FIG. 9B shows theideal situation in which probe marks 908 coincide with the centres ofthe respective lead pads 906. In step 716, the offset is calculated soas to achieve the ideal situation. In particular, the differences in thepositions of the probe marks and the centres of the respective lead padsare first determined. Using these differences, the offset is thencalculated such that if the first electronic device is further adjusted(i.e. further to the rough adjustment in step 708) in the X, Y and θdirections by amounts respectively equal to the X, Y and θ components ofthe offset prior to contacting the probe pins 606, the ideal situationwill be achieved (i.e. the probe marks' positions will coincide with thecentres of the respective lead pads).

In step 718, the first electronic device is transported to theoffloading station 312 by the electronic device holder (again, via therotation of the turret's main circular body) and is then offloaded fromthe apparatus 300.

Step 802 is performed next. Referring to FIG. 8, in step 802, a furtherelectronic device is loaded onto the loading station 302.

In step 804, the further electronic device is transported to the firstimaging station 304 and a first image of the further electronic deviceis captured by the uplook camera 402. This is performed in a similarmanner as that described in step 704 above.

In step 806, the position of the further electronic device relative tothe electronic device holder is determined by the processing moduleusing the first captured image.

In step 808, the further electronic device is transported to theadjusting station 306 and the position of the further electronic deviceis adjusted. This is performed in a manner similar to that described instep 708 above, except that in step 808, the adjustment is done usingnot only the position of the further electronic device relative to theelectronic device holder, but also the offset calculated in step 716.More specifically, in step 808, a device positioning difference isdetermined by calculating the difference between the further electronicdevice's position relative to the electronic device holder and the firstelectronic device's position relative to the electronic device holder(after the rough adjustment in step 708). Then, after the furtherelectronic device is placed onto the second movable element 508, theprocessing module sends signals to the adjusting station 306 to drivethe motors of the XYT table 502 to perform the following: (i) rotate thesecond movable element 508 by an amount equal to the sum of the θcomponent of the offset and the θ component of the device positioningdifference, (ii) move the first movable element 506 along the X axis byan amount equal to the sum of the X component of the offset and the Xcomponent of the device positioning difference and (iii) move the firstmovable element 506 along the Y axis by an amount equal to the sum ofthe Y component of the offset and the Y component of the devicepositioning difference. This adjusts the position of the furtherelectronic device with respect to the electronic device holder.

In step 810, the further electronic device is transported to thecontactor station 308 to perform a testing process on the furtherelectronic device. This is done in a similar manner as that described instep 710, except that the further electronic device needs to be urgedagainst the probe pins 606 only once, thereby forming probe marks of asecond level of depth less than the first level of depth.

In step 812, the further electronic device is transported to theoffloading station 312 and is then offloaded from the apparatus 300.

Steps 802-812 are then repeated on a further plurality of electronicdevices. In particular, the apparatus 300 is configured to perform steps802-812 on a predetermined number of subsequent electronic devices(after the first electronic device). Thereafter, steps 702-718 arerepeated on another electronic device to obtain another offset (whichmay or may not be the same as the previous offset) and using thisoffset, steps 802-812 are performed on yet another predetermined numberof subsequent electronic devices.

FIG. 10 shows an apparatus 1000 for aligning probe pins with respect topositions of electronic devices according to a second embodiment of thepresent invention. The apparatus 1000 is similar to the apparatus 300and thus, the same parts will have the same reference numerals with theaddition of prime.

As shown in FIG. 10, the apparatus 1000 also comprises a loading station302′, a first imaging station 304′, a second imaging station 310′, anoffloading station 312′ and a transfer member 314′. However, instead ofhaving separate stations 306, 308 for adjusting the positions of theelectronic devices and for contacting the devices with the probe pins606, these two stations are integrated to form a single adjusting andcontactor station 1002 in the apparatus 1000. More specifically, thissingle adjusting and contactor station 1002 comprises the probe pins andis configured to adjust positions of the probe pins.

FIG. 11A shows a perspective view of an XYT table 1102 of the singleadjusting and contactor station 1002. The XYT table 1102 comprises firstand second movable elements 1104, 1106 similar to the first and secondmovable elements 506, 508 of the apparatus 300. The XYT table 1102 alsocomprises a socket 1108 (similar to the socket 604 of the apparatus 300)integrated with the second movable element 1106. FIG. 11B shows anenlarged view of the socket 1108. As shown in FIG. 11B, the socket 1108comprises a plurality of probe pins 1110 on its base.

In use, the apparatus 1000 performs a method as shown in FIGS. 12-13 foraligning probe pins with respect to positions of electronic devices. Themethod performed by the apparatus 1000 is similar to that performed bythe apparatus 300 shown in FIGS. 7-8.

However, instead of step 708 of performing a rough adjustment of thefirst electronic device's position, the apparatus 1000 performs step1208 of performing a rough adjustment of the positions of the probe pins1110. This is done by moving the first and/or second movable elements1104, 1106 of the XYT table 1102.

Also, the offset in step 1216 for the apparatus 1000 is calculateddifferently from that in step 716 for the apparatus 300. Morespecifically, in step 1216, the offset is calculated such that if priorto the testing process, the probe pins are further adjusted (i.e.further to the aforementioned rough adjustment) in the X, Y and θdirections by amounts respectively equal to the X, Y and θ components ofthe offset, the probe marks' positions will coincide with the centres ofthe respective lead pads of the first electronic device.

Further, instead of step 808 of adjusting the further electronicdevice's position using the offset, the apparatus 1000 performs step1308 of adjusting the probe pins' positions using the offset. Morespecifically, in step 1308, a device positioning difference (being thedifference between the further electronic device's position relative tothe electronic device holder and the first electronic device's positionrelative to the electronic device holder) is calculated. Then, theprocessing module sends signals to the single adjusting and contactorstation 1002 to drive the motors of the XYT table 1102 to perform thefollowing: (i) rotate the second movable element 1106 by an amount equalto the sum of the θ component of the offset and the θ component of thedevice positioning difference, (ii) move the first movable element 1104along the X axis by an amount equal to the sum of the X component of theoffset and the X component of the device positioning difference and(iii) move the first movable element 1104 along the Y axis by an amountequal to the sum of the Y component of the offset and the Y component ofthe device positioning difference. This adjusts the positions of theprobe pins. Note that when step 1308 is first performed, the probe pinsare in the position after performing the rough adjustment in step 1208and the probe pins are moved back to this position after each iterationof steps 1302-1312.

For the apparatus 1000, the position of each electronic device relativeto the electronic device holder is fixed at the point the electronicdevice holder retrieves the device at the loading station 302′. Thus,adjusting the positions of the probe pins 1110 adjusts the relativepositions between the electronic devices and the probe pins 1110.

FIG. 14 shows an apparatus 1400 for aligning probe pins with respect topositions of electronic devices according to a third embodiment of thepresent invention. The apparatus 1400 is similar to the apparatus 300and thus, the same parts will have the same reference numerals with theaddition of double prime.

To elaborate, the apparatus 1400 also comprises a loading station 302″,an adjusting station 306″, a contactor station 308″, an offloadingstation 312″ and a transfer member 314″. However, instead of having twoimaging stations 304, 310, the apparatus 1400 comprises only a singleimaging station 1402 configured to capture images of the electronicdevices.

In use, the apparatus 1400 performs a method, similar to that performedby the apparatus 300, for aligning probe pins with respect to positionsof electronic devices. However, the initial and further images of thefirst electronic device are both captured at the single imaging station1402 instead of at separate imaging stations 304, 310. This involvesrotating the main circular body of the turret in a direction opposite tothe direction from the imaging station 1402 to the contactor station308″ (i.e. clockwise in FIG. 14) to move the first electronic deviceback to the imaging station 1402 after the contact stamping processafter turning anti-clockwise to bring the first electronic device to thecontactor station 308″.

FIG. 15 shows an apparatus 1500 for aligning probe pins with respect topositions of electronic devices according to a fourth embodiment of thepresent invention. The apparatus 1500 is similar to the apparatus 300and thus, the same parts will have the same reference numerals with theaddition of triple prime.

To elaborate, the apparatus 1500 also comprises a loading station 302′″,an offloading station 312′″ and a transfer member 314″. However, similarto apparatus 1000, instead of having separate adjusting and contactorstations 306, 308, the apparatus 1500 comprises a single adjusting andcontactor station 1504. Also, similar to the apparatus 1400, instead ofhaving two imaging stations 304, 310, the apparatus 1500 comprises onlya single imaging station 1502 configured to capture images of theelectronic devices.

In use, the apparatus 1500 performs a method similar to that performedby the apparatus 1000 as described above, except that the apparatus 1500captures both the initial and further images of the first electronicdevice at the single imaging station 1502 (in a manner similar to thatdescribed above for apparatus 1400).

Various modifications will be apparent to those skilled in the art.

For example, the various apparatus 300, 1000, 1400, 1500 need not beconfigured to adjust the positions of the electronic devices or theprobe pins in three directions X, Y, θ. Instead, the said apparatus 300,1000, 1400, 1500 may be configured to adjust the positions of theelectronic devices or the probe pins in only two directions X, Y. Inthis case, instead of the XYT table 502, 1002, the adjusting member maybe in the form of an XY table having only a single movable elementsimilar to the first movable elements 506, 1104 of the XYT tables 502,1002.

Also, the positions of the electronic devices or the probe pins may beadjusted by moving the movable elements of the adjusting membermanually. This may be in place of or in addition to the adjustment ofthe positions by driving the motors of the XYT tables 502, 1002. In thiscase, the adjusting station may further comprise a gauge configured tofacilitate the manual adjustment so as to improve the accuracy of theadjustment.

In addition, instead of urging the first electronic device multipletimes against the probe pins so as to form deeper probe marks, a greaterurging force may be used to achieve a similar effect of increasing thevisibility of the probe marks.

Further, it is not necessary to include the step 708, 1208 of performinga rough adjustment of the first electronic device or the probe pinsprior to the contact stamping process on the first electronic device. Inthis case, the offset will be calculated and the adjustment of thedevice's position or probe pins' positions will be subsequentlyperformed without taking into consideration any rough adjustment.

Although not preferred, it is also not necessary to perform the step704, 1204 of capturing an initial image of the first electronic deviceand the step 706, 1206 of determining the position of the firstelectronic device relative to the electronic device holder. Similarly,it is not necessary to perform the step 804, 1304 of capturing a firstimage of each further electronic device and the step 806, 1306 ofdetermining the position of the further electronic device relative tothe electronic device holder. Instead, it may be assumed that theelectronic device holder picks up an electronic device in the sameposition each time, so the position of each further electronic devicerelative to the electronic device holder is the same as the position ofthe first electronic device relative to the electronic device holder.With this assumption, the device positioning difference need not becalculated in step 808, 1308 and the position of each further electronicdevice or the positions of the probe pins can be adjusted by using onlythe offset. In fact, with such an assumption, the positions of the probepins may be adjusted only once using the offset before step 802, 1302 iscarried out for the first time.

The invention claimed is:
 1. A method for aligning probe pins withrespect to positions of electronic devices, the method comprising:conducting contact stamping on a first electronic device with the probepins multiple times repeatedly at a same position of the probe pinsrelative to the first electronic device to form deeper first probe markson lead pads of the first electronic device; capturing an image of thefirst electronic device; determining positions of the first probe markson the first electronic device using the captured image; calculating anoffset using the positions of the first probe marks; adjusting relativepositions between a subsequent plurality of electronic devices and theprobe pins using the offset; and contacting lead pads of the subsequentplurality of electronic devices with the probe pins for testing saidelectronic devices, the contacting of the lead pads of the subsequentplurality of electronic devices with the probe pins forming second probemarks, wherein the first probe marks have a different characteristicthan the second probe marks, and wherein the different characteristic isthat the first probe marks formed during the contact stamping areconfigured to have greater visibility as compared with the second probemarks.
 2. The method according to claim 1, further comprising thefollowing steps prior to the step of conducting contact stamping on thefirst electronic device with the probe pins: retrieving the firstelectronic device with a handling member; and determining a position ofthe first electronic device relative to the handling member.
 3. Themethod according to claim 2, wherein the step of adjusting the relativepositions between the subsequent plurality of electronic devices and theprobe pins using the offset comprises: retrieving a subsequentelectronic device with the handling member; determining a position ofthe subsequent electronic device relative to the handling member;calculating a difference between the position of the subsequentelectronic device relative to the handling member and the position ofthe first electronic device relative to the handling member; andadjusting the relative position between the subsequent electronic deviceand the probe pins using the offset and the calculated difference. 4.The method according to claim 3, wherein the step of adjusting therelative position between the subsequent electronic device and the probepins is conducted by an adjusting station that is integrated with acontactor station for testing the electronic device such that theadjusting station and the contactor station form a single station. 5.The method according to claim 4, wherein the step of adjusting therelative positions between the subsequent plurality of electronicdevices and the probe pins using the offset further comprises the stepof adjusting positions of the probe pins using the single station. 6.The method according to claim 3, wherein the step of adjusting therelative position between the subsequent electronic device and the probepins is conducted by an adjusting station that is separate from acontactor station for testing the electronic device.
 7. The methodaccording to claim 6, wherein the step of adjusting the relativepositions between the subsequent plurality of electronic devices and theprobe pins using the offset is performed by the adjusting station withrespect to the handling member prior to the contacting of the lead padsof the subsequent plurality of electronic devices with the probe pins.8. The method according to claim 2, wherein the step of determining theposition of the first electronic device relative to the handling membercomprises capturing an image of the first electronic device anddetermining the position using the captured image.
 9. The methodaccording to claim 8, wherein the step of capturing the image of thefirst electronic device prior to the step of conducting contact stampingon the first electronic device with the probe pins and the step ofcapturing the image of the first electronic device after the step ofconducting contact stamping on the first electronic device with theprobe pins are conducted using a single imaging station.
 10. The methodaccording to claim 8, wherein the step of capturing the image of thefirst electronic device prior to the step of conducting contact stampingon the first electronic device with the probe pins is conducted usingone imaging station and the step of capturing the image of the firstelectronic device after the step of conducting contact stamping on thefirst electronic device with the probe pins is conducted using anotherimaging station.
 11. The method according to claim 1, further comprisingadjusting a relative position between the first electronic device andthe probe pins prior to the step of conducting contact stamping on thefirst electronic device with the probe pins.
 12. The method according toclaim 1, wherein the step of calculating the offset comprisesdetermining differences in the positions of the first probe marks andcentres of respective lead pads of the first electronic device the firstprobe marks are formed on.
 13. The method according to claim 1, whereinthe first probe marks are formed to have a first level of depth and thesecond probe marks have a second level of depth, the second level ofdepth being less than the first level of depth.
 14. The method accordingto claim 1, wherein the step of adjusting the relative positions betweenthe subsequent plurality of electronic devices and the probe pins usingthe offset is conducted manually using an adjusting station including agauge configured to facilitate manual adjustment of positions of theelectronic devices or the probe pins.
 15. An apparatus for aligningprobe pins with respect to positions of electronic devices, theapparatus comprising: a contactor station configured to conduct contactstamping on a first electronic device with the probe pins multiple timesrepeatedly at a same position of the probe pins relative to the firstelectronic device to form deeper first probe marks on lead pads of thefirst electronic device and to contact lead pads of a subsequentplurality of electronic devices with the probe pins to conduct testingof the subsequent plurality of electronic devices with the probe pins,which testing forms second probe marks, the first probe marks having adifferent characteristic than the second probe marks, and the differentcharacteristic is that the first probe marks formed during the contactstamping are configured to have greater visibility as compared with thesecond probe marks; an imaging station configured to capture an image ofthe first electronic device after the contact stamping of the firstelectronic device with the probe pins; a processing module configured todetermine positions of the first probe marks on the first electronicdevice using the captured image and to calculate an offset using thepositions of the first probe marks; and an adjusting station configuredfor adjusting relative positions between the subsequent plurality ofelectronic devices and the probe pins using the offset prior to thetesting of the subsequent plurality of electronic devices with the probepins.